Many of the automotive EGR systems in use today use exhaust gas back pressure sensitive EGR systems. That is, the changes in exhaust pressure, the intake manifold vacuum, and the position of the EGR valve are monitored partially by means of pressure sensors to control the movement of the EGR valve as a function of the changes in the various parameters as the engine operating conditions change.
Exhaust gases contain water vapor, among other impurities, that pass with the exhaust gases against the pressure sensor movable parts. In colder climates, the water vapor turns to ice causing the pressure sensor to malfunction, which then may cause the EGR valve not to operate as scheduled to provide control of the emissions, The end result is an erroneous output from the sensor, with a very high replacement rate of the pressure sensors in the field.
The invention provides the ability to isolate an EGR pressure sensing device, either electrical or mechanical, from water condensation found in the exhaust gases.